One of your salespeople gets the lead and presents your product to the homeowners. No sale. They're "be backs." What happens to the lead? Does the salesperson hang onto it until the mythical day arrives and the homeowners call to inform him that they are, indeed, interested in buying windows? Or does it disappear forever into his briefcase while he's running the two or three other appointments per day your company is giving him?
Often, turnover is a sign that your hiring, training, or compensation must be modified to improve productivity, but you'll never know what to change if you don't conduct exit interviews with departing salespeople.